We are new to chickens and recently got three chicks. They were all hatched on April 26th, so they are about 4 weeks old now. One of the three is now over twice the size of the other two. Even her feet are huge! She is so large (fat) that she cannot balance on a perch while the other two jump up and down and roost just fine. I am beginning to wonder if there is something wrong or if the smaller two are bantams or something. Any ideas? The smaller two are a gild sex link and a Silver laced wyandotte. The big girl, who we now call butterball is supposed to be a buff araucana.